This invention relates to a method of laminating tire components on a segmental tire building drum which has a plurality of circumferentially spaced, radially movable base segments, each of which has a secondary segment that is radially movable relative to the base segment. This construction provides a crowned surface on the drum to compensate for the thick edges of the components which are applied to the drum and for supporting each of the tire components as it is applied and spliced on the drum.
In building tire breaker/belt packages including breaker plies and belt plies, the breaker plies are cut to length and after application to the green tire carcass, butt spliced together. Preferably, each breaker ply is spliced on a cylindrical, flat surface. With conventional cylindrical tire building drums, this is not always possible because the edges of the breaker plies are surrounded by gum strips and as the breaker plies are applied and laminated, the diameter gauge difference between the edges and the center of the belt plies creates a concave surface instead of a cylindrical flat surface as needed for a satisfactory butt splice of the breaker plies. This problem, i.e. wherein the edges and center of the plies are of a different diameter, is of special concern in the efficient automated building of breaker/belt packages, where the breakers are precut to a predetermined length so they can be applied to the drum without stretching them.
In the past, expandable tire building drums have been proposed, such as that shown in U.S. Pat. No. 4,129,927 (""927), where the drum shoulders have been adjustable. However, the drum disclosed in the ""927 patent and other expandable drums known in the art have not disclosed adjusting the contour of the drum with center segments that can be repositioned during application of the various belt components in order to provide a flat application surface for each component in accordance with the present invention.
An object of the present invention is to provide a tire building drum with an adjustable contour and a method of building a tire on the improved building drum as defined in one or more of the appended claims and, as such, having the capability of being constructed and used to accomplish one or more of the following subsidiary objects.
One object of the present invention is to provide a tire building drum with an adjustable contour and a method of using the drum to form a cylindrical flat surface that supports the tire components as they were applied and spliced on the drum.
This invention relates to the construction of a tire building drum especially designed to laminate tire components, such as breaker plies, having thickened edges.
In accordance with one aspect of the invention, there is provided a tire building drum for laminating tire components including a plurality of circumferentially spaced, radially movable base segments. Each of the base segments has a radially movable secondary center segment and operative structure for moving the secondary center segment radially outward relative to each of the base segments a predetermined amount to compensate for an increase in thickness of the edges of the laminated tire components applied to the tire building drum.
In accordance with another aspect of the invention, the tire building drum with a plurality of circumferentially spaced, radially movable base segments has an inner cylindrical drum hub mounted for rotation and an outer cylindrical drum support disposed radially outward from the inner cylindrical drum hub and connected thereto by a circular support plate. Inflatable bladders are disposed between the base segments and the base drum support for urging the base segments radially outward. Each of the base segments has an end flange with an axially extending channel member for retaining a garter spring that extends around the drum hub to urge the base segments radially inward. The base segments also have stop flanges connected to the drum hub and engageable by each channel member for limiting the radially outward movement of each base segment. A nut member is slidably mounted in each base segment and fastened to the secondary center segment for moving the secondary center segment radially inward and outward. A multiple splined shaft member is rotatably mounted on the base segment and threaded in the nut member for radially moving the nut member and the secondary segment. The shaft member is slidably contained in a grooved sleeve member and engageable with a beveled ring slidably mounted on the drum hub. A first ring gear is connected to the beveled ring and is engageable with a spur gear on a shaft extending axially to a second spur gear engageable with gear teeth of positive drive belt pulleys. The latter drive belt pulleys are connected by a differential pulley, which in turn is driven by a servomotor in response to signals from an encoder.
In accordance with still another aspect of the invention, there is provided a method of laminating and splicing tire components having thickened edges on a tire building drum comprising the following steps. A first tire component is placed on a first flat cylindrical drum surface of the building drum of a first diameter and the ends are butt spliced together. The diameter of a center section of the cylindrical drum is increased to position the first tire component to form a second flat cylindrical surface of a second diameter. A second tire component is placed on the second flat cylindrical surface and the opposite ends of the second component are butt spliced together. Next, the diameter of the center section of the drum is increased to position the second tire component to form a third flat cylindrical surface of a third diameter. Then, a third tire component is placed on the third flat cylindrical surface and the ends of the third tire component are butt spliced together.
The method can also include the following steps. The first, second and third tire components are laminated together. The diameter of the tire building drum is decreased the laminated tire components are removed from the tire building drum.